Roger Federer has called on tennis to redouble its efforts in the fight against doping, saying it would be "naive" to think the sport is clear of drugs cheats.

"Naivety says that tennis is clean, the way it's been all the way through," the 17-time grand slam champion 31-year-old told CNN.

"It's pretty good, of course every sport always has some cases. But I think our sport needs to do the upmost to try to make sure the integrity stays and that the fans don't tune into different sports just because they don't trust the players anymore.

"I've always been fighting to make sure we have enough testing."

Several high-profile doping scandals have rocked sport in recent months.

Federer suggested introducing a system similar to the one used in cycling, where an athletes drug test results are kept over a period of time so that the use of a banned substance is more easily detected.

Novak Djokovic, currently the world's top-ranked male tennis player, told reporters at January's Australian Open that he had not been tested in the previous six months.

Federer called for increased funding and testing to ensure transparency.

"More funding, more blood, more urine, you name it -- more funding all across the board," the world No. 2 said.

"Maybe keep samples as well for a long period of time so you can go back and punish those players. The people, or the players, need to be scared if they cheat.

"Of course some players do it by mistake, but unfortunately it falls into the same situation and you have to pay the price for it."

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Despite a legion of younger stars launching an assault on the top of the sport, including the returning Rafael Nadal, Federer is comforted to see his fellow 30-something David Ferrer alongside him in the top five.

"It's nice to see that even though the game has become so physical that the older guys are hanging in there," Federer said.

"I don't know why that is, but I guess my generation of players is really strong. I think at one point at the French Open we had 30-plus players over 30 years in the main draw, which is pretty incredible.

"And it's nice to see that players aren't being pushed out at 27 or 29 because of the physicality in tennis right now."

Federer has also adapted to life as a father, after his wife Mirka gave birth to twin girls in 2009, although his daughters are still too young to fully appreciate who their father is.

"They actually now know winning and losing a little bit," said Federer. "They also understand the practice and the matches now.

"I'm happy I've been able to stay successful ever since I've had the kids, because a lot of the press felt that things weren't going to happen for me after that."

Despite them being just three years old, Federer admitted he has already tried to get his children playing tennis.

"We've tried to put them into lessons, just for their hand-eye coordination and all of that. I think it's important for kids to do all sports if they have an opportunity.," he said.

"I'm a big believer that it's a great lesson in life, so we try to give them opportunities because we can and I think tennis is a great thing, so we'll see if they pick it up."

Meanwhile, Federer's defense of the Dubai Open title ended in semifinal defeat Friday to Czech Tomas Berdych, the man who also upset him at last year's U.S. Open.

Federer held two match points in the second set tiebreak but they both went begging as Berdych won a thrilling match 3-6 7-6 6-4 against the five-time champion.

It set up a final with Serbian No.1 Novak Djokovic, who beat Juan Martin del Potro of Argentina, 6-3 7-6 in the earlier last four clash.

It stretched Australian Open champion Djokovic's unbeaten run to 17 games and he will start warm favorite for Saturday's final, particularly after the exit of World No.2 Federer.

"Pity to lose that one, but Tomas did well to hang in there," said the Swiss maestro.